Spring warmth gave no clear repeated link to the Ringlet-minus-Meadow Brown flight-date gap in England and Wales in 1980-2024

We tested whether April-May warmth had a repeated link to the gap between mean flight dates of Ringlet and Meadow Brown. We paired records at the same sites in England and Wales in 1980-2001 and 2002-2024. Four site-effect models used 14,702 paired site-years. They controlled March warmth, spring rain and time. Gap slopes were -2.07 and -0.18 days per C in England, and -2.02 and -0.24 in Wales. Every four-test interval included zero. Peak-count controls and a quadratic time term did not give a clear repeated link. The early England ordinary interval was below zero, but the later interval was not. This does not prove that species responses changed or that warmth has no effect. Only six sites met the early Wales filter. Country weather, selected sites, missing visits, detection and few weather years limit inference. We test seasonal weather, not pollution, extreme heat or climate-change attribution. The package has raw snapshots, hashes, code, all results and independent numerical checks.

phenology · butterflies · spring temperature · observation bias · paired species · regional replication · null result